This invention is generally in the field of methods and structures for hermetically sealing small reservoirs or apertures in devices.
U.S. Pat. No. 5,797,898, No. 6,527,762, No. 6,491,666, and No. 6,551,838 describe devices for the controlled release or exposure of reservoir contents. The devices include a plurality of reservoirs in which the reservoir contents are contained. For example, the reservoirs could contain drug molecules for release or sensors for exposure. In certain embodiments, these reservoirs have openings that must be sealed to isolate the reservoir contents in each reservoir, to prevent leakage of material from or between any of the reservoirs. In many embodiments, hermeticity is desirable, for example to protect the purity or quality of the reservoir contents. Indeed, for most long-term in vivo applications wherein the microchip device serves as, or is included as part of, an implantable medical device, hermeticity is necessary.
U.S. Pat. No. 6,194,789 discloses a method of hermetic sealing in which an electronic or optoelectronic component is encapsulated in an adhesive and then coated with one or several metallic layers using physical vapor deposition or electroplating. It also discloses interposing multiple layers of adhesives with metallic layers to provide hermeticity and protection for the metallic layers. However, the reference neither relates to MEMS devices and hermetic micro-reservoirs nor addresses issues of biocompatibility, device interaction with drug or patient, and control of polymer deposition.
U.S. Pat. No. 3,932,227 discloses a hermetic seal formed by plating or using a physical vapor deposition technique to deposit a metal onto two inorganic substrates with a narrow gap. The gap is bridged by the deposited metal forming a hermetically sealed assembly. U.S. Pat. No. 6,474,879 discloses the same concept as specifically applied to hermetically sealing a fiber optic cable into ferrule. Again, these references do not address or relate to hermetic sealing of micro-reservoirs, biocompatibility, or device interaction with drug or patient.
U.S. Patent Application Publication 2003/0010808 describes various techniques for hermetically sealing micro-reservoirs. These techniques include high temperature laser or resistive welding, soldering, ultrasonic welding, and metal compression gaskets.
It would be desirable to provide additional or improved methods of hermetically sealing a microchip device or other reservoir devices, particularly for reservoirs containing materials sensitive to elevated temperatures.